Revision with unchanged content. Mental health in the elderly is a topic that draws a lot of research interest. However, researchers call depression in old age a “scientific myth,” for lack of conclusive findings. While some researchers have found that depression is highest among the oldest people. Others found the opposite. To understand this scientific myth, researchers argue that people of different age groups are usually exposed to different stressors, thus controlling for different stressors will lead to different answers. However, there are situations when all age groups are facing the same stressor. For example, wars, natural disasters, economic depressions, and project-induced forced migrations subject people of all ages to the same adverse conditions. Does the same stressor affect people of different ages differently? In this study, our interest is to detect whether there are any age differentials in depression when individuals of different ages face a common stressor: the impending forced migration-induced by a large scale dam project—the Three Gorges Project (TGP) in China. The book is addressed to professionals in the filed of migration study. It is also directed towards policy makers.